Working example

tests/071-example1.vtc

+varnishtest "Test varnish-devicedetect"
+
+server s1 {
+       rxreq
+       txresp
+} -start
+
+# this example shows how to normalize the user agent string seen by the backend.
+varnish v1 -vcl+backend {
+    include "${projectdir}/../devicedetect.vcl";
+    sub vcl_recv { call devicedetect; }
+
+    sub append_ua_device {
+        if (req.http.X-UA-Device) { 
+            set bereq.http.X-UA-Device = req.http.X-UA-Device; }
+    }
+
+    # This must be done in vcl_miss and vcl_pass, before any backend request is
+    # actually sent. vcl_fetch runs after the request to the backend has
+    # completed.
+    sub vcl_miss { call append_ua_device; }
+    sub vcl_pass { call append_ua_device; }
+
+    # so, this is a bit conterintuitive. The backend creates content based on the normalized User-Agent,
+    # but we use Vary on X-UA-Device so Varnish will use the same cached object for all U-As that map to
+    # the same X-UA-Device.
+    # If the backend does not mention in Vary that it has crafted special
+    # content based on the User-Agent (==X-UA-Device), add it.
+    # If your backend does set Vary: User-Agent, you may have to remove that here.
+    sub vcl_fetch {
+        if (req.http.X-UA-Device) {
+            if (!beresp.http.Vary) { # no Vary at all
+                set beresp.http.Vary = "X-UA-Device"; 
+            } elseif (beresp.http.Vary !~ "X-UA-Device") { # add to existing Vary
+                set beresp.http.Vary = beresp.http.Vary + ", X-UA-Device"; 
+            } 
+        }
+        # comment this out if you don't want the client to know your classification
+        set beresp.http.X-UA-Device = req.http.X-UA-Device;
+    }
+
+    # to keep any caches in the wild from serving wrong content to client #2 behind them, we need to
+    # transform the Vary on the way out.
+    sub vcl_deliver {
+        if ((req.http.X-UA-Device) && (resp.http.Vary)) {
+            set resp.http.Vary = regsub(resp.http.Vary, "X-UA-Device", "User-Agent");
+        }
+    }
+} -start
+
+client c1 {
+	txreq -hdr "User-Agent: Mozilla/5.0 (Linux; U; Android 2.2; nb-no; HTC Desire Build/FRF91) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1" 
+	rxresp
+	#expect bereq.http.User-Agent == "mobile-android"
+	expect resp.http.X-UA-Device == "mobile-android"
+	expect resp.http.Vary == "User-Agent"
+}
+
+client c1 -run